/*

 * Licensed to the Apache Software Foundation (ASF) under one

 * or more contributor license agreements.  See the NOTICE file

 * distributed with this work for additional information

 * regarding copyright ownership.  The ASF licenses this file

 * to you under the Apache License, Version 2.0 (the

 * "License"); you may not use this file except in compliance

 * with the License.  You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

package com.bff.gaia.unified.sdk.extensions.euphoria.core.client.accumulators;



import com.bff.gaia.unified.sdk.extensions.euphoria.core.annotation.audience.Audience;

import org.slf4j.Logger;

import org.slf4j.LoggerFactory;



import java.time.Duration;

import java.util.concurrent.atomic.AtomicBoolean;



/**

 * Placeholder implementation of {@link AccumulatorProvider} that may be used in executors as a

 * default.

 */

@Audience(Audience.Type.EXECUTOR)

public class VoidAccumulatorProvider implements AccumulatorProvider {



  private static final Logger LOG = LoggerFactory.getLogger(VoidAccumulatorProvider.class);



  private VoidAccumulatorProvider() {}



  public static Factory getFactory() {

    return Factory.get();

  }



  @Override

  public Counter getCounter(String name) {

    return VoidCounter.INSTANCE;

  }



  @Override

  public Counter getCounter(String namespace, String name) {

    return VoidCounter.INSTANCE;

  }



  @Override

  public Histogram getHistogram(String name) {

    return VoidHistogram.INSTANCE;

  }



  @Override

  public Histogram getHistogram(String namespace, String name) {

    return VoidHistogram.INSTANCE;

  }



  @Override

  public Timer getTimer(String name) {

    return VoidTimer.INSTANCE;

  }



  // ------------------------



  /** AccumulatorProvider Factory. */

  public static class Factory implements AccumulatorProvider.Factory {



    private static final Factory INSTANCE = new Factory();



    private static final AccumulatorProvider PROVIDER = new VoidAccumulatorProvider();



    private static final AtomicBoolean isLogged = new AtomicBoolean();



    private Factory() {}



    public static Factory get() {

      return INSTANCE;

    }



    @Override

    public AccumulatorProvider create() {

      if (isLogged.compareAndSet(false, true)) {

        LOG.warn("Using accumulators with VoidAccumulatorProvider will have no effect");

      }

      return PROVIDER;

    }

  }



  // ------------------------



  /** Empty implementation of Counter doesnt count anything. */

  private static class VoidCounter implements Counter {



    private static final VoidCounter INSTANCE = new VoidCounter();



    private VoidCounter() {}



    @Override

    public void increment(long value) {

      // NOOP

    }



    @Override

    public void increment() {

      // NOOP

    }

  }



  /** Empty implementation of Histogram doesnt count anything. */

  public static class VoidHistogram implements Histogram {



    private static final VoidHistogram INSTANCE = new VoidHistogram();



    private VoidHistogram() {}



    @Override

    public void add(long value) {

      // NOOP

    }



    @Override

    public void add(long value, long times) {

      // NOOP

    }

  }



  /** Empty implementation of Timer doesnt measure anything. */

  public static class VoidTimer implements Timer {



    private static final VoidTimer INSTANCE = new VoidTimer();



    private VoidTimer() {}



    @Override

    public void add(Duration duration) {

      // NOOP

    }

  }

}